Diver{3 s breathing apparatus with gas purifying system

ABSTRACT

A diver&#39;&#39;s breathing apparatus comprises a mouthpiece, a canister of carbon dioxide absorbing medium, two tubes linking the mouthpiece and the canister, one permitting flow of exhaled gas to the canister and the other permitting flow of purified gas to the mouthpiece. Two more tubes extend between the canister and an inflatable bag. One allows gas to flow into the bag and the other allows gas to flow back to the canister. The apparatus further comprises a high pressure oxygen cylinder to maintain a sufficient oxygen concentration in the system. Non-return valves in said tubes ensure that virtually all exhaled gas passes twice through the canister before being rebreathed.

[ Dec. 30, 1975 DIVERS BREATHING APPARATUS WITH GAS PURIFYING SYSTEM [76] Inventor: Terence Barrington Paul, 72

Carmen Drive, Carlingford, New South Wales, Australia, 2118 [22] Filed: June 25, 1974 [21] Appl. No.: 482,966

[30] Foreign Application Priority Data Feb. 6, 1974 Australia 6482/74 [56] References Cited UNITED STATES PATENTS 2/1952 Lambertsen 128/142.6 1/1973 Guzay 128/191 R FOREIGN PATENTS OR APPLICATIONS Germany 128/191 R 188,612 11/1922 United Kingdom 128/191 Primary Examiner-Richard A. Gaudet Assistant ExaminerHenry J. Recla Attorney, Agent, or Firm-Mason, Fenwick & Lawrence [57] ABSTRACT A divers breathing apparatus comprises a mouthpiece, a canister of carbon dioxide absorbing medium, two tubes linking the mouthpiece and the canister, one permitting flow of exhaled gas to the canister and the other permitting flow of purified gas to the mouthpiece. Two more tubes extend between the canister and an inflatable bag. One allows gas to flow into the bag and the other allows gas to flow back to the canister. The apparatus further comprises a high pressure oxygen cylinder to maintain a sufficient oxygen concentration in the system. Non-return valves in said tubes ensure that virtually all exhaled gas passes twice through the canister before being rebreathed.

11 Claims, 13 Drawing Figures US. Patent Dec. 30, 1975 Sheet 2 of5 3,929,127

US. Patent Dec. 30, 1975 Sheet 3 of5 3,929,127

US. Patent Dec. 30, 1975 Sheet 4 of5 3,929,127

157 //a 5 L I [-12 Z;

US. Patent Dec. 30, 1975 Sheet 5 of5 3,929,127

Fig. 12.

DIVERS BREATHING APPARATUS WITH GAS PURIFYING SYSTEM This invention relates to breathing apparatus of the kind in which the user inhales from a breathing bag to which make-up oxygen is fed from a high pressure storage bottle and exhales into the bag through a carbon dioxide absorber. Such apparatus are used largely by underwater swimmers to achieve little or no release of exhaust bubbles from the system to betray the divers whereabouts.

A major disability in known breathing apparatus of this type is that the last portion of any exhaled gas has not passed through the absorber when the user begins to take his next breath. Consequently, this last volume of gas will be inhaled in an untreated form. It is a primary object of this invention to ensure that virtually no gas that has just been expelled will be rebreathed and that nearly all inhaled gas will have passed through the absorber at least twice.

To this end the invention consists in breathing apparatus comprising two gas conduit loops sharing a common portion over part of their length, which portion is adapted to hold a gas purifying substance, means for permitting only unidirectional motion of gas through said loops, a mouthpiece located in one of said loops, a gas tight inflatable bag forming part of the other loop and means for admitting make-up gas to the apparatus.

So that the invention may be more readily understood, two preferred embodiments will be described by way of example only and with reference to the accompanying drawings in which:

FIG. 1 shows a diagrammatic arrangement of a breathing apparatus according to one embodiment of the invention.

FIG. 2 presents an end view of a canister constituting the common portion of the two loops of the apparatus of FIG. 1.

FIG. 3 is a sectional side elevation of the canister of FIG. 2 taken on line 3=3 of that figure.

FIG. 4 is a partly sectioned view taken on line 4-4 of FIG. 2.

FIG. 5 is a side elevation of an adjustable pressure relief valve fitted to the inflatable gas tight bag of the apparatus of FIG. 1.

FIG. 6 is a plan view of the valve shown in FIG. 5.

FIG. 7 is a sectional view of the valve of FIG. 6 taken on line 7=7 of that figure.

FIG. 8 is a partly sectioned side elevation and according to the invention is similar to FIG. 3.

FIG. 9 is an end view of the canister illustrated in FIG. 8, looking in the direction indicated by line 9=9 of FIG. 8.

FIG. 10 is a sectional end view taken on line 10=l0 of FIG. 8.

FIG. 11 is a sectional end view taken on line 11=11 of FIG. 8.

FIG. 12 is an enlarged longitudinal section taken on line 12=12 of FIG. 9.

F llglGg. 13 is a sectional view taken on line l3=13 of Referring now to FIGS. 1 to 7 it can be seen that the mouthpiece 1 of the breathing apparatus cornmuni= cates with ports 9 and 10 in a canister 5 via check valves 2 and 3 and a flexible breathing hose 4. This arrangement defines the first of the two gas conduit loops. The second loop is formed by a gas tight inflat= 2 able bag 6 opening into the canister by means of ports 7 and 8. In this way the canister forms the common portion of the two gas conduit loops referred to above.

The arrangement of check valves 2 and 3 in this particular embodiment will ensure that any gas in the mouthpiece loop can only move in an anticlockwise direction around the circuit, while motion in the bag loop as shown is similarly restricted to an anticlockwise sense by the check valves 7 and 8.

In operation, the canister 5 is filled with any suitable carbon dioxide absorbant and a separate oxygen cylinder 13 is connected as shown at 11 via a pressure reducing valve 12. This valve will pass just enough makeup oxygen to replace that consumed in the users respiratory system as the carbon dioxide he produces is gradually absorbed by the absorbant in the canister.

As the diver inhales through the mouthpiece 1 the pressure within the system will be reduced and oxygen will pass through the constant mass flow reducing valve 12 and into the canister at the connection 11. From here, it will pass out of the canister to the mouthpiece through opening 10 as it follows an anticlockwise path through the hose 4. Due to the arrangement of check valves 2 and 3 the exhaled gas will return to the canister via port 9 since check valve 3 will now be closed-The increased pressure in the canister will close check valve 7. In this condition, with valves 3 and 7A closed, the exhaled gas is compelled to pass right through the absorbant in the canister and then into the inflatable bag through port 8 and check valve 8A. 0n the next intake of breath, the pressure within the canister will again be reduced, but now the action of external ambient pressure on gas in the inflatable bag will close check valve 8A forcing the gas to enter the canister through port 7 via the open check valve 7A. From this valve the gas is once again compelled to travel the full length of the canister, through the absorbant and into the mouthpiece via opening 10 and check valve 3. Check valve 2 ensures that the last portion of the previously exhaled breath cannot return to the mouthpiece without first passing through the absorbant in the canister.

It will be appreciated that when the breathing device is used by a diver it will be subjected to changes in gas working pressure as the divers depth varies. To this end it is desirable to incorporate a pressure relief valve in the system to regulate the operating gas pressure to suit any particular operating conditions. In the embodiment shown in FIG. 1 this relief valve is indicated by reference 17 and is located in the inflatable gas tight bag 6.

One example of the valve itself can be seen in more detail in FIGS. 5, 6 and 7.

The relief valve comprises a hollow cylindrical body 20 mounting a pressure adjusting screw 26. The adjusting screw is turned by means of a knob 19 and acts upon an axially movable disc 24 via a suitable spring 23. This disc 24 in turn bears upon a diaphragm 25 resting on a perforated disc located in the valve body 20 by a ring nut 29. The pressure relief valve itself is sealed into an opening in the inflatable bag 6 by means of a ring nut 21 which securely clamps the bag material against a flange on the valve body 20. A gas tight seal is promoted by the O ring 22 retained in an annular groove in the clamping face of the ring nut 21.

Should an increase of pressure in the inflatable bag 6 cause the pressure difference across the relief valve 17 to vary by more than a set amount, the net pressure acting on the diaphragm will overcome the spring force and open the relief valve to permit any excess gas in the inflatable bag to escape into the valve body 20 and pass out through exhaust holes 27. Once this is accomplished the spring loaded disc 24 will force the diaphragm 25 back onto its seat and thereby cut off the flow of exhaust gas. The disc 24 is provided with sufficient radial clearance to enable any escaping gas to pass around it.

Referring in particular to FIGS. 2 and 3, the canister 5 shown in the present embodiment comprises a cylindrical centre portion 16, the open ends of which are sealed by two removable end caps 15 secured by clamping bolt 18. Removal of the end caps is achieved by extending the fold away handle 14 and unscrewing the nut 30 from the clamping bolt 18.

Each end cap is provided with two ports, 7 and 9 in one end cap and 8 and in the other. Ports 7 and 8 admit gas to and from the inflatable bag 6 while the remaining ports 9 and 10 communicate with the mouthpiece hose 4. As both end caps are essentially the same in FIG. 3, it will suffice to describe the construction of ports 8 and 9 only.

Port 9 is identical with port 10 and comprises a port liner 34 which is pressed into the end cap against sealing O-ring 33 and held by ring nut 50. This port liner 34 also serves to retain a captive knurled ring nut 35 which is free to rotate and removably connect the mouthpiece air hose 4 to the canister 5. It does this by screwing onto a flanged sleeve 37 which is then drawn up into sealing engagement with the outer end face of port liner 34 against an O-ring 36. The O-ring 36 is recessed into an annular groove on the clamping face of the flanged sleeve 37 as an aid to sealing, the inner surface of the flanged sleeve 37 is threaded to accept a flanged tubular connecting piece 39 and O-ring 38. As these two components are screwed together, the air hose is securely clamped by the two projecting flanges as shown in FIG. 3.

Port 8 is identical with port 7 and comprises a port liner 48 which is drawn into the end cap 15 against O-ring 47 by ring nut 49 to retain a captive knurled ring nut 46. A flanged spiggot 42 is sealed into the inflatable bag 6 by means of a ring nut 40 which clamps the bag material against an O-ring 41 bearing on the flange in the spiggot 42. The captive knurled ring nut 46 draws the flanged spiggot 42 into sealing engagement with the outer face of the port liner 48. In the same way as the flanged sleeve 37 of port 9, the flanged spiggot 42 has an O-ring 43 recessed into an annular groove on its sealing face.

The port liner 48 and flanged spiggot 42 also serve to locate a check valve 8A. This valve comprises a perforated disc 45 recessed into the port liner 48 and sup= porting a flexible diaphragm 44. In the configuration shown, the permitted flow of gas through the ports is that indicated by the arrows, assuming that the mouth= piece conduit loop contains check valves arranged as shown in FIG. 1.

It will be appreciated that both the inflatable bag and the mouthpiece hoses can be readily disconnected from the canister of the present embodiment by simply un= screwing the appropriate captive ring nut 46 or 35.

Referring more particularly to FIGS. 2 and 4, make= up oxygen from a reservoir 13, is admitted to the canis= te'r by means of a hose (not shown) which screws into a connector 11 located in the upstream and cap. This placement is desirable should it become necessary to flush the canister thoroughly with pure oxygen.

The common portion of the two gas conduit loops is illustrated by FIGS. 8 to 13 inclusive. In FIGS. 8 to 13 components corresponding to those of the embodiment described earlier bear reference numerals greater than those in FIGS. 1 to 7. In This embodiment, the common portion is again in canister form and comprises a cylindrical centre portion 116 that locates against O-rings 32 in annular sealing grooves 131 out into the two end caps and 151. The ends caps are held on the cylinder ends by means of a clamping bolt 118 and nut 130. In this case however, all connections with the exception of the oxygen inlet are made to the one end cap 151.

The two conduit loops, though not completely shown, are still serviced by 4 ports, 107, 108, 109, 110 having the same relationship to the overall circuit as the ports in the preceding embodiment carrying the corresponding reference numbers. Thus, ports 109 and 110 contain no valves and connect with the mouthpiece hose by means of clips which clamp the hose into projecting flanged sleeves 158. Each flanged sleeve 158 screws into the end cap 151 and seals against O-ring 159.

Ports 107 and 108 are adapted to communicate with the inflatable gas bag and in a similar way to the mouthpiece loop connections, these ports also comprise a projecting flanged sleeve portion 161 which screws up against an O-ring seal 163 in the end cap 151. In this case however, each sleeve portion 161 retains a check valve 107A or 108A which may be of the same diaphragm construction as described earlier. The check valve is located by an internal sleeve 162 which is clamped against the valve by a ring nut 164 which screws into counterbore in the flanged sleeve 161.

The ports 108 and 110 pass completely through the end cap 151 and open into the main body of the canister, while the remaining ports 107 and 109 communi' cate with a chamber 156 formed inside the end cap itself. This chamber in turn opens into a hollow cylindrical cup 157 which is threaded at its closed end and screws into a corresponding threaded portion on the clamping bolt 118. As the thread is tightened, the cylindrical cup is drawn into the end cap 151 to seal against O-ring 165.

The open end of the cylindrical cup 152 is sealed over one end of a long central pipe 152 which extends almost to the other end cap, at which point it opens into the canister body. This pipe 152 also supports a pair of perforated discs 153 which are located on the pipe 152 towards each end of the canister and serve to retain the gas purifying substance in an annular space 166 from which it cannot escape to contaminate the airways or valves. The arrangement is such that any gas entering the canister through ports 107 or 109 can only reach the annular space 166 by travelling through the central pipe 152 and emerging at the open end of the pipe adjacent and cap 150, as shown by the arrows in FIG. 8.

The general sequence of events during operation of the present embodiment is similar to that described with reference to FIG. 1 and requires only a brief review to explain the function of the different canister:

Exhaled gas will again enter the canister via port 109 but it will then pass through the chamber 156 in end cap 151 and move into the central pipe 152. After travelling through the full length of the pipe it emerges into the annular space 166 as shown by the arrows in FIG. 8. From here it must pass through the entire length of the annular space containing the gas purifying substance before it enters the inflatable bag through port 108 and check valve 108A.

As the diver inhales, external water pressure forces the partly purified gas out of the inflatable bag via check valve 107A, through port 107 and back into the chamber 156 in end cap 151. From here, the gas moves once again down the central pipe 152 and completely through the purifying substance a second time before leaving the canister via port 110 en route to the mouthpiece.

Make-up oxygen in this case is admitted to the system through hose connection 111 located in end cap 150 at the upstream end of the canister.

Although the invention has been described by reference to two specific embodiments it is understood that those skilled in the art will readily perceive many additional variations of the inventive concept as defined by the appended claims. For example, if diaphragm check valves are used, they might all be located away from the canister or common portion of the gas conduit loops provided that the prerequisite gas flow pattern has been defined. Similarly there is no need for the common portion to be cylindrically shaped, nor for the conduit loops to communicate with it through one or more caps.

The claims defining the invention are as follows:

1. A breathing apparatus comprising a first and a second gas conduit loop, a gas purifier chamber which forms a common portion of the two gas conduit loops over part of their length, a gas purifying substance contained within said chamber, means for permitting only uni-directional flow of gas through each of said loops and the gas purifier chamber, a mouthpiece orifice located in the first of said loops, a gas tight inflatable bag forming part of the second of said loops and means for admitting make-up gas to the apparatus whereby the gases flowing into the mouthpiece orifice flow through the gas purifying substance twice in the same direction before being returned to the mouthpiece orifice.

2. A breathing apparatus as claimed in claim 1 wherein said gas purifier chamber is a canister having at least one removable end cap.

3. A breathing apparatus as claimed in claim 2 wherein the canister contains two end caps each of which contains two ports for communication with the gas conduit loops.

4. A breathing apparatus as claimed in claim 3 wherein each of the two ports in either end cap communicates with a different conduit loop.

5. A breathing apparatus as claimed in claim 3 wherein the two ports of each end cap communicate with one and the same conduit loop.

6. A breathing apparatus as claimed in claim 3 wherein both conduit loops communicate with the canister by means of ports in one end cap only.

7. A breathing apparatus as claimed in claim 6 wherein said end cap contains four ports, two of which pass directly into the canister while the remaining two communicate with a duct opening into the canister at a point adjacent the far end of the canister.

8. A breathing apparatus as claimed in claim 1 wherein said means for permitting only uni-directional flow of gas through said loops and gas purifier chamber comprises one pair of check valves located in the. first loop on either side of the mouthpiece orifice and a second pair of check valves located in the second loop on either side of the gas tight inflatable bag with said pairs of check valves oriented to cause the uni-directional flow of gases in each loop to flow in the same directions through the gas purifier chamber.

9. A breathing apparatus as claimed in claim 1 in which the means for admitting make-up gas to the apparatus comprises a high pressure gas reservoir communicating with the apparatus through a pressure reducing valve.

10. A breathing apparatus as claimed in claim 9 in which the make-up gas enters the apparatus at an upstream end of the gas purifier chamber.

11. A breathing apparatus according to claim 1 in which the gas tight inflatable bag is provided with an adjustable pressure relief valve. 

1. A breathing apparatus comprising a first and a second gas conduit loop, a gas purifier chamber which forms a common portion of the two gas conduit loops over part of their length, a gas purifying substance contained within said chamber, means for permitting only uni-directional flow of gas through each of said loops and the gas purifier chamber, a mouthpiece orifice located in the first of said loops, a gas tight inflatable bag forming part of the second of said loops and means for admitting make-up gas to the apparatus whereby the gases flowing into the mouthpiece orifice flow through the gas purifying substance twice in the same direction before being returned to the mouthpiece orifice.
 2. A breathing apparatus as claimed in claim 1 wherein said gas purifier chamber is a canister having at least one removable end cap.
 3. A breathing apparatus as claimed in claim 2 wherein the canister contains two end caps each of which contains two ports for communication with the gas conduit loops.
 4. A breathing apparatus as claimed in claim 3 wherein each of the two ports in either end cap communicates with a different conduit loop.
 5. A breathing apparatus as claimed in claim 3 wherein the two ports of each end cap communicate with one and the same conduit loop.
 6. A breathing apparatus as claimed in claim 3 wherein both conduit loops communicate with the canister by means of ports in one end cap only.
 7. A breathing apparatus as claimed in claim 6 wherein said end cap contains four ports, two of which pass directly into the canister while the remaining two communicate with a duct opening into the canister at a point adjacent the far end of the canister.
 8. A breathing apparatus as claimed in claim 1 wherein said means for permitting only uni-directional flow of gas through said loops and gas purifier chamber comprises one pair of check valves located in the first loop on either side of the mouthpiece orifice and a second pair of check valves located in the second loop on either side of the gas tight inflatable bag with said pairs of check valves oriented to cause the uni-directional flow of gases in each loop to flow in the same directions through the gas purifier chamber.
 9. A breathing apparatus as claimed in claim 1 in which the means for admitting make-up gas to the apparatus comprises a high pressure gas reservoir communicating with the apparatus through a pressure reducing valve.
 10. A breathing apparatus as claimed in claim 9 in which the make-up gas enters the apparatus at an upstream end of the gas purifier chamber.
 11. A breathing apparatus according to claim 1 in which the gas tight inflatable bag is provided with an adjustable pressure relief valve. 